Fat is evil. Carbs are evil. Fructose is evil. Gluten is evil. Meat is unhealthy. Vegetarians are unhealthy. You have to eat ‘clean’ to be healthy.
Absolute statements like this fill the nutrition and health headlines but are always off the mark. These and other extreme positions fail because they do not allow for the moderate forces of dose and context to enter the discussion. Much like absolutist positions in religion and politics, these beliefs are seductive because they oversimplify things and give people black and white rules on which to hang. When people employ these rules and see body or health improvements, their false beliefs are confirmed and they become emotional advocates for the position.
This is why anyone who posts a reasoned, evidence-based article pointing out the flaws in The China Study will likely be marked as an ‘enemy’ by vegetarians and flocked with attacks. It is also why the same kind of articles pointing out flawed ideology in the Paleo Diet or the fallacies behind ‘Clean Eating’ receive the same type of ire. People tend to take their own nutrition and exercise regimes very personally when they have seen seemingly good results from using them. Nutrition and workout become religion and any variance from their paths becomes blasphemy. This is also why I tend to get puzzled looks from audiences when I don’t place myself in the camp of any one diet or exercise program as the gospel. It can be much more seductive and simple to espouse one way of eating and exercising as ‘the best’ and draw a line in the sand. But it is also dishonest to do so.
A much more honest and effective way to objectively look at nutrition and health is to take dose and context into account. These are moderating forces that allow rules to be flexible, avoid absolutes and extremes, and generally ensure a healthier, happier eating experience in the long term. To be clear, dose means AMOUNT- and yes it does make a difference how much or little of something you are consuming and how often you are consuming it. Context means what ELSE are you consuming most of the time, what is your INDIVIDUAL SITUATION in terms of background, body weight, medical issues, allergies, digestion, food preferences, individual goals, psychology, lifestyle, etc. and countless other contextual factors that must be taken into account.
The Perils of Ignoring Dose and Context
For some simple examples at how we go wrong with ignoring dose and context- take a look at this well-intentioned lecture concerning the evils of fructose in the modern diet. The take home message is that fructose in all forms is a cause of obesity, diabetes, and metabolic syndrome. This message is echoed by some nutrition authors and advisers who are weary of fructose even in whole fruits and vegetables regardless of dose and context. This can be very counterproductive advice to give new clients who are learning how to eat and fuel their bodies properly. Instilling food fears and guilt is not a healthy way to teach someone what to eat. The flaws in that presentation were pointed out well by Alan Aragon here and the comments again are filled with zealots defending the fructose is evil argument.
Super Size It!
Ignoring dose and context can also lead us astray in terms of foods or exercises that are thought to be good for us. Especially here in the land of super-sizing everything, people often mistakenly think that if some of something is good, then a lot of it is even better. When some health benefits of soy became highly touted in the 1990′s after studying certain long-living Asian populations, we suddenly saw a surge in soy products lining the shelves. Lots of people began substituting processed soy milk, soy protein, soy everything for fresh whole foods formerly in their diets. But the traditional use of soy in traditional Asian diets (such as the Okinawans) was quite moderate in terms of daily consumption and the form of soy eaten was mostly fermented tofu and fresh soybeans. The dose and context of soy consumption by traditional cultures was ignored and the message somehow became- eat soy and lots of it! Well, not surprisingly, it has turned out that there is now a mountain of evidence showing the health problems that can be caused by overeating soy products.
Food Extremists
We also see this neglect of dose and context in the extreme all-or-nothing response. This line of thinking says that if a lot of something is bad for you, then any of it is bad for you. An example is seen in raw food purists who refuse to eat anything that has been cooked or heated above a certain temperature, regardless of food type or method of cooking. While it’s true that there are health benefits from consuming a portion of your food as raw vegetables and fruits, and that cooking can leech some nutrients from foods, this is extended to mean that cooking of anything is bad for you and that ONLY raw food should be eaten to stay healthy. This is an extreme position that often leads to serious malnutrition and digestive problems- and is wholly unnecessary in order to be healthy.
This all-or-nothing mindset seems to also be suffered by those who demonize certain food groups or macronutrients across the board. We are only recently recovering from decades of fat-phobia, the incorrect and harmful assumption that eating dietary fat is what makes us fat and causes heart disease and diabetes. Some poorly interpreted epidemiological studies resulted in the conclusion that dietary fat not only correlated with heart disease, it caused it. The old correlation is not causation problem. The context in which fat was consumed was ignored, the differences between different types of dietary fat was not taken into account, and the removal of healthy fats from the diet often results in substituting high levels refined carbohydrates, only making things worse.
Pot Calling the Kettle Black
I should note that those on the other sides of these arguments can be just as guilty of ignoring dose and context and taking extreme positions. Avid meat eaters can get too religious about their holy red meat and start making claims that all vegetarians are unhealthy, too skinny, and dying of malnutrition. The fact is, these days many people are able to stay quite healthy, lean, and strong without eating red meat or any meat for that matter. Many different things work for lots of different people. There are some basic nutrition and caloric requirements, but those can be obtained in a variety of healthy ways. It’s hard for some people to wrap their heads around that fact.
Current Trend: Carb Phobia and Demonizing Grains
We are not learning from history in demonizing an entire macronutrient because these days it seems we have moved from fat to carbohydrates as the ‘evil food group’. The same mistakes are being made again, as extremists tout very-low or even zero carb diets as the best way to health. Much like the raw food purists, the low-carb Taliban takes a reasonable concept of moderating carbohydrate intake relative to the SAD, and warps it by advocating complete removal of an entire macronutrient from the diet. This line of thinking can be extended to many advocates of the Paleo Diet, which demonizes all wheat/grains as ‘neolithic’ foods that we are not evolved to digest properly and which always cause health problems. Few would argue that refined flour and wheat is overeaten by many SAD-eaters and should be reduced to make room for more nutritious lower calorie foods. It’s also true that a small minority of the population suffers from celiac disease and other forms of gluten intolerance and should avoid wheat completely. But many Paleo folks view wheat as the devil incarnate for everyone, even those who are not celiacs and do not have demonstrable gluten sensitivity issues. While getting into the arguments for and against the Paleo Diet will be covered in an upcoming post, suffice it to say for now that I think it can be a very healthy diet as long as flexibility and moderation are allowed. Many of the speculative claims behind the diet are problematic, not necessarily the food choices. However, many people stay quite healthy and lean not following a Paleo Diet and regularly including grains, legumes, dairy, and other ‘forbidden’ foods. Carbophobia (and fat-phobia and other food phobias) can be an unhealthy mindset for lifelong eating, creating unnecessary stigmas around certain foods and possibly depriving a person of important nutrition.
So the next time a sweeping headline comes across the screen touting the health benefits of a superberry or the dangers of bacon or the secret to youth found in a population, remember to check for dose and context in the claims and don’t be seduced by extreme positions and over-simplified rules. They aren’t necessary to eat delicious, healthy food and they aren’t healthy for most of us in the long-run.
*My caveat: When beginning with new clients who are overweight and have food issues, I will often start with a strict diet to break them of some harmful habits surrounding problem foods, ensure they are getting nutritional requirements met, and help them eat within their caloric needs more easily. So there is a place for strict rules, but temporarily, not for life. I’m also certainly not against someone getting great results, so if adopting a strict eating plan works better psychologically for someone because they have trouble with moderation, by all means don’t fix it if it’s not broken- but please don’t start advocating your extreme regime for everyone else. That’s when the problems arise.
The (missing) role of genetics and genomics in nutrition research
I’m a little late to discovering his blog and work but Keith Grimaldi at Eurogene has some excellent thoughts in this post about why most human nutrition research is pretty weak, inconclusive, and misses the boat much of the time. This line of thinking really struck a chord with me because ever since I’ve transitioned from my work in laboratory neurobiology to nutrition, I’ve been quite frustrated with the quality of the research evidence cited by many top nutrition folks to support their positions.
Grimaldi points out that many nutrition experiments are designed with too many confounding variables at play, and with goals directed more toward finding out what ’causes’ or ‘prevents’ cancer and chronic diseases. Because we still understand so little about exactly how/why people get cancer, trying to look at what a few thousand people eat and then trace whether or not they end up getting cancer is a very imprecise and problematic schema. Grimaldi proposes that a better option would be to pay attention to different genotypes present in the subjects that may interact with the foods to trigger or protect against DNA damage. How often do I read a nutrition paper about vegetables or processed meats or red wine in which the genetic variance among the subjects is taken into account? Not very.
When this approach is used, some very interesting and more precise information can be found. Take, for example the difference in methods and approach between these 2 studies:
While the first study has a much grander scale, ambition, and cost, it turned out to be pretty pointless in the end. In hindsight, it was probably doomed from the beginning. Grimaldi’s point is that trying to figure out with one grand study if eating more fruit and veggies will prevent cancer for everyone is a failing proposition. The genotypes of the participants, clearly important in discovering those who are more vulnerable to DNA damage, were not taken into acocunt. Nor were multiple variables concerning the types of fruits and veggies and methods of preparation, etc. Further, the line between DNA damage and developing cancer is still a murky one, with much left to be understood. Perhaps a more modest but precise goal of looking at DNA damage would be of more value than simply these cohort studies that use questionaires and trace trajectories of who gets sick and who doesn’t over the years.
Certainly, some politics and money come into play here- just look at the titles of the two papers and the headlines generated by each (I’m guessing not many for the Palli paper). We may need to adjust our goals and expectations for what can be discovered by any single study, just like the rest of the science world already has. For some reason nutrition research often endeavors to solve the whole puzzle in one bluntly designed, imprecise, inconclusive study rather than take small steps toward discovery with many smaller, more precise, attainable studies. They may not be as exciting individually, but the understanding that could be gained with confidence seems a lot greater.
Of course there is more to how we end up than simply looking at our genotypes. I’m not proposing a reductionist view that should only look at the role of genes in nutrition and illness. It’s true that epigenetics, the way our behavior influences our gene expression, plays a role, but it is still poorly understood. That is exactly what more studies paying attention to genetics may help us understand.
Hopefully, we’ll see genetics and genomics start playing a bigger role in the larger, well-funded nutrition studies. Part of the problem is undoubtedly the lack of interdisciplinary cooperation between nutrition science researchers and those in genetics, bioinformatics, molecular biology, and even neuroscience. Great things can happen when cross-fertilization between disciplines and research methods occurs. Good food for thought, and hopefully a better framework to consider the next time you see another nutrition cohort study touted in the news.